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where singleton class used in java

 
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where singleton classes are used in j2ee web application.can we use it for connection pooling.
 
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A Singleton class is used when you want only ONE instance of a class to be available in your application.

Yes, Database Connection Pooling would be a good example of its use case.
For example you could have a singleton class called DBConnectionPoolManager, with methods like getConnection, returnConnection etc. It can have a getInstance static method to return the only instance that exists of the class.
 
Rajendra Prakash
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Hi Friend, Thanks alot for your reply
 
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Note that the Singleton pattern has really fallen out of favor; see http://faq.javaranch.com/java/SingletonPattern for more information.

Connection pooling is not such a good example. Complex enterprise apps frequently need to access multiple databases - in which case you'd need a pool manager instance for each DB.
 
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I've developed the MultipleSingleton pattern for just this use, in fact.

Step 1: Develop MultipleSingleton pattern.
Step 2: ???
Step 3: Profit!!!
 
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